fix dict warnings for R18

Remove warnings for:

```bash
yamerl/include/yamerl_types.hrl:56: Warning: type dict/0 is deprecated and will be removed in OTP 18.0; use use dict:dict/0 or preferably dict:dict/2

yamerl/include/internal/yamerl_constr.hrl:69: Warning: type dict/0 is deprecated and will be removed in OTP 18.0; use use dict:dict/0 or preferably dict:dict/2
```